The present invention relates to electrical cables and, more particularly, to a multiconductor cable for ultra-low impedance electrical interconnections. The invention has particular utility for use in audio applications and will be described in connection with such utility, although other uses are contemplated.
Cables used in low impedance applications such as connecting power supplies to loads and audio amplifiers to speakers can suffer with respect to their performance capabilities in critical applications due to three factors--inductance, capacitance, and skin effect. All these factors are frequency dependent and result in, basically shifts in the time of arrival of the components of a signal as a function of frequency. For audiophiles who are into true high fidelity performance, such frequency shifting due to, for example, skin effect in the interconnecting cables can result in what is perceived as a muddied signal to the listener. In such applications, it has been typical to employ cables such as the coaxial cable 10 of FIG. 1. Coaxial cable 10 has a central conductor 12 surrounded by a core of insulating material 14 over which is disposed an outer conductor 16 covered by insulation 18. The outer conductor 16 is typically a spirally wrapped metal foil or an encasing shield of wire braid. In applications of relatively low impedance, i.e., less than the standard 150 ohm lamp cord or 50 ohm transmission line, heavy cable such as that indicated as 22 in FIG. 3 or multi-strand heavy wire such as that indicated as 20 in FIG. 2 have been employed. In such low impedance applications, the emphasis has usually been on heavy gauge conductors such as those of FIGS. 2 and 3 as the best attempt to solve the problem.
While considering the problem of connecting dynamic loads to power supplies in a power supply test system as employed with computers manufactured by the assignee of this application, the applicant noted that an instantaneous step in the load current contained high frequency harmonics and that employing traditional cables resulted in the cable inductances being high enough that power supplies would fail a step response test due to the transient created by the cabling. Applicant first considered applying strip-line techniques as employed in high frequency applications such as microwave and radar to the problem. The major drawback to such an approach was that many layers would be needed and that the forming (bending) of such a conductor would be very difficult. Cables used for interconnecting must be bendable and, preferably, even flexible in use.
Wherefore, it is the object of the present invention to provide a low impedance cable for use in ultra-low impedance applications having predetermined inductance, capacitance, and skin effect characteristics.
It is another object of the present invention to provide such a cable which is bendable and possibly even flexible in use.
It is still another object of the present invention to provide a connector system for use with the cable.
Other objects and benefits of the present invention will become apparent from the detailed description which follows hereinafter taken in conjunction with the drawing figures which accompany it.